What is the general gear meshing clearance?
2 Answers
3ml~4ml. The existence of tooth side clearance will cause impact between teeth, affecting the smoothness of gear transmission. Therefore, this clearance can only be very small, usually ensured by tooth difference. For gear motion design, it is still designed without tooth side clearance (zero backlash). Backlash classification: 1. Normal backlash: The shortest distance between the non-working tooth surfaces when the working tooth surfaces of two gears are in contact. 2. Circumferential backlash: In a pair of meshing gears, when one gear is fixed, the maximum arc length of the pitch circle that the other gear can rotate. 3. Meshing backlash: When a pair of meshing cycloidal gears and pin gears are in the theoretical meshing position, the shortest distance measured between the cycloidal gear tooth profile and the pin gear tooth profile on the line connecting the center of a pin tooth and the node. 4. Tooth side clearance: The tooth side clearance of a gear refers to the circumferential play of the other gear when one gear of an assembled gear pair is fixed, measured by the arc length on the pitch circle.
The concept of gear backlash is quite familiar to me as an automotive enthusiast. It refers to that tiny gap between two gears, typically controlled within a range of 0.05 to 0.1 millimeters. This value isn't fixed—it depends on the specific gear type and application scenario. For instance, in transmissions, too little clearance may cause gears to jam, wear excessively, or overheat, while excessive clearance can generate noise and reduce transmission efficiency. Having studied various vehicle specifications, I know new cars usually maintain around 0.08mm clearance through precision engineering. However, wear over time or bearing issues can expand this gap beyond 0.15mm, affecting driving smoothness. Regular gear oil maintenance and inspections are crucial—I recommend owners have professionals measure it with a micrometer during biennial servicing to ensure safe parameters and avoid costly repairs. By the way, temperature fluctuations also affect clearance, requiring extra attention during significant seasonal variations between winter and summer.
